As in the case of humans, the optimum response of a mechanical, electromechanical, electronic, or other device to a present event can, in many cases, be optimized by taking into account the response made by the device to that historical event most closely matching a current event. Identification of the appropriate historical event can be accomplished by matching information representing the current event with information representing each of a series of past events and identifying that past event which is best correlated with the current event. A technique for doing this optically and the theory involved are described in THE FOUNDATION OF EMPIRICAL KNOWLEDGE, WITH A THEORY OF ARTIFICIAL INTELLIGENCE, Pieter J. van Heerden, N.V. Uitgeverij Wistik-Wassenaar, The Netherlands, 1968 and in U.S. Pat. Nos. 3,296,594 issued Jan. 3 1967 to van Heerden for OPTICAL ASSOCIATIVE MEMORY and 3,492,652 issued Jan. 27, 1970 to the same patentee for OPTICAL ASSOCIATIVE MEMORY SYSTEM.